Pi-factor cases

[TonyMac32]

Since I've a pile of these boards lying about, and really prefer a proper case to a plastic one, I have one particular one that stood out to me:

 

https://www.amazon.com/gp/product/B079CF5FNX/

 

The case is aluminum, with machined end blocks and a perforated top.  This would be my recommendation for any hot board like the Tinker Board, and to be honest the one I bought is quite nicely put together, with a somewhat industrial feel.

 

Does anyone else have a favorite?  I'm not really talking about those zebra cases or open-air acrylic/standoff sandwiches.

[Igor_K]

Yes it was a great one (It is available on aliexpress also https://www.aliexpress.com/item/Raspberry-Pi-3-Aluminum-Case-Silver-Case-Metal-Enclosure-for-RPI-3-Model-B-Compatible-with/32825338978.html) 

 

I bought this one https://www.aliexpress.com/item/Raspberry-Pi-3-Model-B-Cast-Aluminum-Case/32683284505.html I'm waiting for shipping still. I hope I would provide a better heatsink without a fan. 

[tkaiser]

Since when conducting some own tests almost 3 years ago (just to realize that tons of small vents resulted in no difference compared to no vents) I would be interested in a real 'thermal performance' comparison.

 

Ensure that ambient temperature is the same. Boot the board, wait 5 minutes and monitor idle temperature (10 lines from 'armbianmonitor -m' are sufficient). Let armbianmonitor continue to run and start in another terminal 'stress -c 4'. Wait until temperature doesn't further increase (10 min should usually be sufficient). Then put board into enclosure and repeat the whole test. If board has a lot of vents repeat the test again covering all vents so no airflow possible. Provide average temperature values from last 10 armbianmonitor lines for each idle and 'light load' (stress) for each situation.

 

Pro variant: Repeat all tests with board/enclosure standing upright instead of lying flat on a surface.

 

And of course the whole test is a joke when ambient temperature is not exactly identical  

[chwe]

18 minutes ago, tkaiser said:

And of course the whole test is a joke when ambient temperature is not exactly identical  

• And when air flow 'in the open variant' differs.
• And when throttling differs e.g. power consumption
• And when thermal readouts aren't correct

I never played with thermals but I think that a Miner would be better to monitor thermals (you get some sort of benchmark under high load) and a small script to ensure that 'the same tasks where done' could help to do it 'scientifically'... 

[off-topic]

Spoiler

In chemistry this is called 'reaction calorimetry'. Those are the guys which perform mostly a way less reaction than every other technician cause this needs a proper set up to generate meaningful results (not that they are lazy, it just needs a lot of preparation to do it properly). A 'runaway' reaction is only funny when a small British guy from Topgear does it...  

 

The not so funny runaway reactions which come to my mind are Bhopal and Chernobyl (okay this was more for the physics but calorimetry don't give a f.. where the heat comes form)...

Cause this is offtopic anyway... let's see some capacitors blowing up..  

 

[/off-topic]

 

48 minutes ago, Igor_K said:

I bought this one https://www.aliexpress.com/item/Raspberry-Pi-3-Model-B-Cast-Aluminum-Case/32683284505.html I'm waiting for shipping still. I hope I would provide a better heatsink without a fan. 

a cool case but the SoC and some other components have to much perfect for a good passive cooling or at least those pillows shouldn't break the board...  

 

50 minutes ago, Igor_K said:

Yes it was a great one (It is available on aliexpress also https://www.aliexpress.com/item/Raspberry-Pi-3-Aluminum-Case-Silver-Case-Metal-Enclosure-for-RPI-3-Model-B-Compatible-with/32825338978.html) 

from the pictures it seems that the chinese forgot the wiring out for the 40pin header as it is possible with @TonyMac32s case..

[tkaiser]

21 minutes ago, chwe said:

 

1 hour ago, tkaiser said:

And of course the whole test is a joke when ambient temperature is not exactly identical  

• And when air flow 'in the open variant' differs.
• And when throttling differs e.g. power consumption
• And when thermal readouts aren't correct

You got the reason I was asking for 'stress -c 4' and not 'a miner' since lightweight enough to not totally trash the whole idea.

 

And yeah, 'air flow' in the open variants is what's to be expected. This is not that interesting than the comparison between 'enclosure with lots of vents' and 'same enclosure with venths covered' but it's always a nice reminder that approx. 100% of enclosures increase heat since almost all SBC are constructed wrongly.

[guidol]

2 hours ago, chwe said:

• from the pictures it seems that the chinese forgot the wiring out for the 40pin header as it is possible with @TonyMac32s case..

 

How about the FLIRC / KODI case which does support the 40 pin cable? 
https://www.raspberrypi.org/forums/viewtopic.php?f=40&t=158309

[TonyMac32]

2 hours ago, Igor_K said:

I bought this one https://www.aliexpress.com/item/Raspberry-Pi-3-Model-B-Cast-Aluminum-Case/32683284505.html I'm waiting for shipping still. I hope I would provide a better heatsink without a fan.

 

I have that for the Pi3.  Being so specific, I didn't list it, but it performs well.

 

Logging ambient, internal case temperature, SoC temp, and controlling cpu processes, it can be determined what the rate of power dissipation is.  A decent approximation of the thermal energy input can be made by measuring power consumption.

 

An improvement on this case would be holes on the lower side to allow proper convection

[chwe]

A small excursion into thermodynamics - cause 'in theory' this affects more or less all the stuff related to 'why my shitty case heats up my board'.

 

Let's assume that those cases fully enclosure the board (which is wrong) cause calculations are horrible hard when we talk about openings and 'heatbridges' etc.... Let's also assume that the heat is spread perfectly inside the case, means no 'hotspots' which is for sure false (e.g. SoC). The only possible ways to spread out heat will be heat transfer through material which is determined by material & thickness (thermal conductivity in K⋅m⋅W−1 should be the 'most interesting' number):

PMMA (also known as acrylic, plexiglas etc.): 0.193 at 0-50ºC (source)

PLA (if you print it on your own): 0.1-0.25 (source, this depends also on additives which ist then polymere chemistry - a field I'm not an expert...  , I would say, we're more on the 0.1 than on the 0.25 side of this range)

high density Polyethylene (often used for those cheap cases): ~0.5 (source)

Aluminium: 237 (boom, game changer..  only copper and diamond would be better in case you have enough money.. )

Steel (carbon): 36-54 (source)

Steel (stainless): 16-24 (source)

 

and now, the most interesting one

Air: ~0.024

 

And this is where @tkaiser is right  with the 'almost all SBC are constructed wrongly' statement, as long as we don't bring the heat from the hotspots properly to the case, there's no chance for a proper cooling. We can enlarge the surface of the SoC with a small passive cooler but inside an enclosure this shouldn't have a big effect as long as we don't have active transport to spread the heat out or make as much holes as we can for convection (I left aside the convection calculation stuff to the engineers cause it's to painful... ). 

From a heat dissipation point of view,  metal cases makes 'most' sense when there's a bridge between the hotspots and the case otherwise I would assue (and I don't have 'scientific' evidence) that there's no big benefit...

When the board isn't in a enclosure, convection will play a much bigger role than thermal conductivity whereas convection tends to go to zero the more the housing is closed...

 

A footnote for the self-printed PLA cases, keep in mind that PLA gets conductive at ~70°C, if a hotspot is near to the case this can short your board... 

 

Edit:

If you use those small 'shitty' cases you should really dig into @tkaiser 'minimal consumption research'... The less your board consumes, the less heat is generated...

[tkaiser]

On 3/21/2018 at 8:28 PM, guidol said:

How about the FLIRC

 

https://youtu.be/mBSfb6vlfKo?t=6m37s

 

Can only be used with one specific board since onboard components on predecessors or successors have partially different position and height. If SBC vendors would start to do it less weird they would put the SoC and other parts that generate heat (eg. SATA controllers or PMICs) on bottom PCB side so that they're the highest and add some thermal compound. If case designers then would simply combine one somewhat thick aluminium base plate with a plastic top the problem would already be solved. Not even heatsink fins necessary.

 

I tested this with those boards where it works this way: Banana Pi, Banana Pro, NanoPi NEO[2], ODROID HC1 and HC2 (the RK3328 Cloudmedia Transformer never arrived here unfortunately). Large aluminium surface to spread the heat is all it needs.

 

[TonyMac32]

Yeah, I second tkaiser on the flirc, just like that nice cast one, it's Pi specific. 

It would be ideal to have a large thermal mass for most situations, although surface area is still important for sustained loads (bear in mind my brain gets stuck in 30-100watt dissipation situations, so the fins may be utterly unnecessary here).  Use the proper thermal tape to make up the space or copper spreaders...

 

[chrisf]

1 hour ago, chwe said:

and now, the most interesting one

Air: ~0.024

 

 

The difference though, is air is a gas so in addition to thermal conduction, there is convection.

 

I imagine you'll get better thermal performance if your sealed enclosure has a fan inside it, increasing the thermal transfer between the air and SoC/heatsink and the air and case.

[TonyMac32]

19 minutes ago, chrisf said:

 

The difference though, is air is a gas so in addition to thermal conduction, there is convection.

This is a given, and per Chwe:

 

2 hours ago, chwe said:

I left aside the convection calculation stuff to the engineers cause it's to painful...  

 

Well, I was being the good engineer and ignoring the math in favor of measurement.  ;-)

[chwe]

1 hour ago, tkaiser said:

Large aluminium surface to spread the heat is all it needs.

you don't sell any small fans anymore if you do it 'the right way'... 

 

I think the 'let's do it the RPi way' is also one of the reasons.. And maybe we should ask the EEs how complicated this is for all this 'high speed' interfaces (e.g. GbE)..  The espressoBin has it on the backside too (as a more recent one).. If you don't make the case 'as small as possible', famous OPi zero example:

 

Or if you use the right fans it shouldn't be such a issue.. Notebooks with plastic cases are working too as long as the fans and the heatpipes woring properly. 

 

30 minutes ago, TonyMac32 said:

proper thermal tape

so not the one delivered by ASUS...  When possible I prefer thermal paste (forget about good old days when I shortened my new AMD CPU with silver paste....  those 'not protected' CPUs were nasty...)

 

 

27 minutes ago, chrisf said:

The difference though, is air is a gas so in addition to thermal conduction, there is convection.

Sure you have..  It's related to 'brownian motion'  and that's why calculation of convection can be so nasty (I wouldn't trust in my convection etc. calculations in detail - left it for the engineers which has a penchant for it,  but I'm quite sure that I'm familiar enough with the concepts in behind)...  But the smaller the case and the fact that most cases try to be 'as close as possible' for no understandable reason (they aren't water or dust proof anyway) makes it hard for convection. In comparison to a desktop PC (and I don't talk about this NUC small as possible stuff you can buy), SBC cases are a way smaller as they should be...  

 

Edit:

[offtopic]

Quote

I was being the good engineer and ignoring the math in favor of measurement.  ;-)

 It's called the 'elon musk approach': 

 

And to be clear, I think they have amazing engineers at spaceX...  

[TonyMac32]

11 minutes ago, chwe said:

And to be clear, I think they have amazing engineers at spaceX...  

 

I know a few, they're not too bad.  

[Igor_K]

I've got a practical reason to prefer a unibody case.  It is a dust. My RPI3 is a media center for my family. It lives behind my TV or it travels with us. In both cases, I would prefer something without too many vents. 

 

If it does not fit well I hope I will be able to fix it with thermal glue and copper plates. 

[arox]

On 3/21/2018 at 4:59 AM, TonyMac32 said:

I'm not really talking about ... open-air acrylic/standoff sandwiches.

 

Why not ?

 

Either the board designer provides (**) an efficient solution as with odroid HC1/HC2, either you have to rely on convection, and then an "open case" with at least ventilation holes. And then an "acrylic sandwitch" that lets see a pretty sbc is as good as a pretty aluminium box.

 

(**) They "rely" on community for software. They cannot also leave power supply, storage and heat dissipation problems on consumer's charge !

 

N.B. I have tried to enclose a BPIM2+ in an aluminium box without holes, and I can confirm it is a very bad solution for the reasons explained by chwe.

[TonyMac32]

44 minutes ago, arox said:

Why not ?

I was looking for a discussion on cases, not sandwiches of acrylic.  I can make an acrylic sandwich in my basement using hand tools, not much to talk about there.  ;-). With the size of the Pi community I'm sure there are cases I (and a lot of others) have never seen, so thought I'd start this thread.

[tkaiser]

15 hours ago, TonyMac32 said:

I second tkaiser on the flirc, just like that nice cast one, it's Pi specific

 

But since it's so inefficient (again: https://youtu.be/mBSfb6vlfKo?t=6m37s ) at least it will fit on the new RPi 3 B+. The FLIRC ruins the thermal efficiency of the enclosure material with a huge gap between chips and enclosure filled with thick thermal pads. Since the BCM2387B0 on the new Raspi is higher they'll start to put two thermal pads to the package soon. The old thick and inefficient one for BCM2387 (overheating SoC needing good heat transfer) and a much thinner one for the new board that doesn't need a heatsink anyway. Well done or... it's just a typical 'Rasperry Pi product'. Eye candy and a good feeling and real result inefficient.

 

[chwe]

Convection also depends on 'choose the right passive cooler'. There are different needs if you stick a fan on top of the cooler or not... I prefer self-printed 'stand-foots' with four screws.. A proper thermal design of the board seems to be way to go.. It is possible with small boards (okay, in another price range ).. 

5 hours ago, TonyMac32 said:

I can make an acrylic sandwich in my basement using hand tools

you can, but cutting pmma is often a mess. When sandwich than a wooden one (looks better and heat dissipation to the baseplate doesn't matter)..   

 

Did someone ever test such stuff for cooling? (http://www.versarien-technologies.co.uk)

 

 

at least 'dust free': 

Spoiler

 

[arox]

I think that you need to apply pressure in order to provide a good thermal interface. So I wonder if solution provided by third-party without screw or springs can be efficient and evacuate heat by conduction threw the case ?

[TonyMac32]

I think that you need to apply pressure in order to provide a good thermal interface. So I wonder if solution provided by third-party without screw or springs can be efficient and evacuate heat by conduction threw the case ?

Well, it will be at least as efficient as those thick tapes, or those non-thermally-conductive stickies on most of the RPi ones. A proper thermal tape or, with those cast enclosures, a thermal paste does a good job.
@chwe, look up diacool heat sinks, you'll be entertained.

Sent from my Pixel using Tapatalk

[chwe]

3 minutes ago, TonyMac32 said:

@chwe, look up diacool heat sinks, you'll be entertained.

Put a diamond to your lips..  It never gets warm..  (in case it does, don't  tell your wife that it shouldn't...  )

https://en.wikipedia.org/wiki/Material_properties_of_diamond#Thermal_conductivity

 

Silicon carbide heat sinks could also be worth to test. Did someone ever test the direction how the board stands (playing a bit with convection... )? 

 

8 hours ago, arox said:

N.B. I have tried to enclose a BPIM2+ in an aluminium box without holes, and I can confirm it is a very bad solution for the reasons explained by chwe.

A terrible decision for this tests.. No voltageregulation for CPU makes it prone to overheat anyway..  

[arox]

2 hours ago, TonyMac32 said:

Well, it will be at least as efficient as those thick tapes, or those non-thermally-conductive stickies on most of the RPi ones. A proper thermal tape or, with those cast enclosures, a thermal paste does a good job.
@chwe, look up diacool heat sinks, you'll be entertained.

Sent from my Pixel using Tapatalk
 

 

Maybe there are good and less good thermal pads ... Nevertheless, I remember the old times and the AMD Duron (the cheap version of Athlon - 100W to evacuate). If the heatsink was badly assembled, you could be certain to burn the proc !

 

BTW : have someone tried an odroid XU4 with passive heatsink ?

[tkaiser]

1 hour ago, chwe said:

Did someone ever test the direction how the board stands (playing a bit with convection... )? 

 

Sure. Better results compared to the board lying flat on a pillow

 

Since latest RPi 3+ from last week now also started to copy what those cheap Orange Pi do since years (using the PCB ground plane as massive heatsink) I suggested this test over at RPi forum: https://archive.fo/6kzg0 ... and (not so) surprisingly the post got censored: https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=207863&start=225#p1286503 -- they really don't like it over there their users could get the idea that there grows more than Raspberries on this earth 

 

BTW: really impressive how inefficient the old RPi 3 was and is from a thermal point of view:

 

vs.

[TonyMac32]

Yikes.  And let's be serious for a second, why wouldn't you use a big copper area you need anyway to move heat?  I thought that was normal practice...

[TonyMac32]

1 hour ago, arox said:

BTW : have someone tried an odroid XU4 with passive heatsink ?

There's one on my desk, but I haven't officially tested/stressed it.  I hooked a fan up to see when it thought it should be actively cooling, under load it still does so regularly.

[chwe]

Why should you change a system from what the majority of its buyers is happy?  Let's have a look at the RPi staff (104 people.. ):

-3x hardware engineers. 

-27 'managers' 

-9 software engineers..

 

so, stay focused on what you're good..  They manage their community well, it's another question if they do it in a sane way.  As long as this business model works, there are a few reasons to change it. Which boardmaker supports their board for such a long time in this price-range (it's clear that this ends in drawbacks for the more recent ones)? 

 

47 minutes ago, tkaiser said:

and (not so) surprisingly the post got censored:

Quote

You agree that “Raspberry Pi Forums” have the right to remove, edit, move or close any topic at any time should we see fit.

 

you agreed to it by registration..  I understand that they don't want pictures of its competitors on their web-site, doesn't mean that I think that is a good way but understandable... Forum driven by the boardmaker are mostly focused on their own stuff and part of a business model. 

 

 

[tkaiser]

8 hours ago, chwe said:

Forum driven by the boardmaker are mostly focused on their own stuff and part of a business model.

 

Sure, RPi Trading's mission is to sell mediocre hardware to clueless people. And the forum serves as a way to keep customers dumb. All perfectly fine since their mission is to get money for education and charity and so on. I understand that.

 

Let's look at the thermal image from new RPi 3+ again:

 

In RPi forum the censors do not only censor but also spread BS. Users are told that the HDMI cable acts as an efficient heatsink (well Google image search suggest something else but hey).

 

But if we look at how all modern SBC (now Pi 3+ included) do it then wouldn't it be a good idea with an aluminium enclosure to use a full size conductive thermal pad between enclosure and PCB? In those aluminium enclosures today there's usually air or isolating foam: https://youtu.be/mBSfb6vlfKo?t=1m46s

 

Wouldn't a 2mm thermal pad improve things?

 

 

[manuti]

As seeing on Raspi.tv http://raspi.tv/2018/how-much-power-does-raspberry-pi-3b-use-power-measurements

The new RPi 3+ eat much power than the previous one, and following first law of thermodynamics all the energy supplied (in absence of moving parts) becomes heat. 

Sorry, @tkaiser but I buy one new RPi3+ and I can confirm the SoC run colder but the whole board is warmer than previous RPi. 

[tkaiser]

18 hours ago, manuti said:

one new RPi3+ and I can confirm the SoC run colder but the whole board is warmer than previous RPi

 

Sure, this is how it should work. Great that now even the RPi folks got it

 

Yesterday I 'unboxed' Orange Pi Lite 2 (Allwinne H6). As small as the H3 Lite but extra thick PCB. After 10 minutes of idle operation the whole PCB including all receptacles is warm so the groundplane efficiently spreads the heat away from the SoC. I put 3 low performing heatsinks on SoC, PMIC and DRAM and reported SoC temperature went down from 49°C in idle to 46°C (after waiting the same 10 minutes or until temperature is stable).

 

So still curious how efficient a 2mm thermal pad between PCB lower side and an aluminium enclosure would work (to transport heat out of an enclosure). To be clear: I'm talking about something like this (and am not willing to spend my own time on such tests any more since done with the low consumption/thermal stuff)

 

Testing such stuff with enclosures that already exist seems impossible. The FLIRC is constructed wrongly and to buy the Wicked you must be mad.